A voltage regulator accepts a variable or unknown input voltage and provides a substantially constant output voltage at a regulated level. The stability of the regulated output voltage allows the voltage to be used as a supply voltage for a device load. In some devices, the amount of current drawn by the device load can vary, and it is typically desirable that the output voltage of the voltage regulator be substantially independent of the output current (i.e. the load current). For example, a voltage regulator can supply power to a device load having digital logic, and switching at the logic gates can vary the amount of current drawn by the load. It is typically desirable that the output voltage remain relatively insensitive to changes in the load current due to the switching activity.
One example of a linear voltage regulator is a low-dropout (LDO) regulator, which is characterized by its ability to regulate the output voltage at a low voltage differential between an input and an output of the regulator. A pass element (e.g., a power transistor) is connected in series between the input terminal and the output terminal of the LDO regulator, and provides the load current to the output terminal of the LDO regulator. However, sudden changes in the load current can cause transient changes in the output voltage, resulting in undesirable degradation of performance at the device load.